This application claims the priority of German application 196 22 954.5 filed in Germany on Jun. 7, 1996, the disclosure of which is expressly incorporated by reference herein.
The invention relates to a wheel suspension for a motor vehicle having an axle bracing body which comprises a transversely extending axle tube extending transversely to the driving direction and adjoining, longitudinally extending, additional axle tubes on whose two ends one wheel respectively is disposed and which are supported toward the vehicle body by way of a spring-and-damper element, the transversely extending axle tube being held by way of a center bearing in a cardanically disposed manner on the vehicle body.
From German Patent Document DE 44 19 221 C1, a wheel suspension of a rear axle is known which has an axle bracing body with a central bearing as well as a Watt linkage. Furthermore, from German Patent Document DE 44 22 875 A1, a suspension of a rear axle for a motor vehicle is known which has a stiff axle bracing body which has an axle tube which extends transversely with respect to the driving direction and has wheels disposed on the end side. By way of an elastic bearing arranged in the center, the axle tube is cardanically linked to the vehicle body. The free ends of the axle tube are equipped with an end piece on which the wheels are disposed and are connected with one another by way of A-arms which, by way of a bearing, are held on a bending-resistant control arm which is supported on the vehicle body.
It is an object of the invention to provide a wheel suspension for a rear axle of a motor vehicle which has a simple construction and permits targeted wheel position changes in the case of forces acting upon the wheel as well as in the case of compression and rebounding operations.
According to preferred embodiments of the invention, this object is achieved by providing an arrangement wherein the transversely extending axle tube 3 has at least one softly bending zone in an area of the center bearing, and wherein free ends of the longitudinally extending axle tubes are swivellably connected with transverse struts which are supported on the vehicle body in bearings.
Principal advantages achieved by means of the invention are the fact that the wheel suspension is formed of a U-shaped axle tube which has a center bearing and is connected with the free ends of longitudinally extending axle tubes in each case by means of transverse struts which are linked to the body side in a swivellable manner. These transverse struts cause a supporting of the wheels in the event that forces act upon the wheel.
The transversely extending axle tube of the wheel suspension has a soft zone around the center bearing so that a bending of the axle tube can take place in this zone during suspension operations. This bending movement is required because of the transverse struts which cause a forced guiding of the longitudinally extending axle tubes on a circular path.
This bending movement of the transversely extending axle tube in the case of suspension operations causes a lateral-force understeering and, because of the corresponding arrangement of the bearing points of the transverse struts in the area of the longitudinal center axis of the vehicle on the vehicle body as well as of the ends of the struts facing away on the longitudinally extending axle tubes, the toe-in changes can be varied.
The soft zone in the transversely extending axle tube can, for example, be formed by an interposed, elevated spring leaf or by compressed tube sections. However, embodiments are also contemplated with the axle tube dimensioned such that a bending can occur.
Depending on the type of construction and available space, the transverse struts can consist of struts which extend transversely from a longitudinally extending axle tube to an exterior side member of the vehicle body, or of struts which are disposed approximately in the longitudinal center axis of the vehicle on a member which is connected with the vehicle body.
The center bearing is constructed as a cardanic elastic bearing so that the wheel suspension consisting of the U-shaped axle tube can move mainly about a vertical axis as well as about a transverse axis.
For varying the toe-in changes, for example, in the case of suspension operations in the opposite direction (rolling), particularly when the right wheel rebounds and the left wheel compresses, the bearings of the transverse struts are correspondingly arranged below or above a horizontal plane extending through the center bearing.
In the case of a same-side suspension of the wheels (both rebound or compress), the position of the two transverse struts, viewed from the rear is sloped toward the interior top, whereby a positive toe-in change occurs, or they are sloped toward the interior bottom, whereby a negative toe-in change occurs.
Other objects, advantages and novel features of the present invention will become apparent from the following detailed description of the invention when considered in conjunction with the accompanying drawings.